Search results for "Vinyl alcohol"

Localized surface plasmon resonance sensor based on Ag-PVA nanocomposite thin films

2009

In this work we demonstrate the use of nanocomposite thin films of poly(vinyl alcohol) with embedded silver NPs for chemosensing purposes. Silver NPs are in situ synthesized inside polyvinyl alcohol during the bake step of the formation of a nanocomposite thin film. The polymer in the nanocomposite provides an appropriate chemical and electromagnetic environment for metal NPs in order to interact with and hence detect the chemical species. A limit of detection below 20 nM is found when detecting 2-mercaptoethanol as the analyte, when measuring spectral changes (peak wavelength, linewidth and intensity) in the Localized Surface Plasmon Resonance. Potential qualitative and semi-quantitative s…

Time-monitoring sensor based on oxygen diffusion in an indicator/polymer matrix

2013

Abstract A time-monitoring sensor based on the oxidation of leuco methylene blue (LMB) to methylene blue (MB) was developed. The sensor changes its color from yellow to green in the presence of oxygen and was integrated into a poly(vinyl alcohol) matrix. The diffusion of the oxygen in the polymer matrix as well as the oxygen uptake due to the oxidation reaction determines the time monitoring of the sensor. A physical model has been developed that accounts for both the diffusion as well as the oxidation reaction. For this purpose, the reaction kinetics was determined experimentally. Moreover, the diffusion coefficient of oxygen was determined and concentration profiles in the polymer matrix …

Bio-inspired surface modification of iron oxide nanoparticles for active stabilization in hydrogels

2020

Biological materials employ a variety of dynamic interactions in sophisticated composite structures to function adaptively on different time and length scales. Inspired by such designs we develop a novel surface modification approach to promote dynamic interactions between nanoparticles and polymer chains in physical and double network hydrogels. Physical hydrogels are formed via reversible complexation of borate ions with poly(vinyl alcohol) (PVA) and chemical crosslinks are introduced by electron beam irradiation. Dopamine is used for surface modification of magnetic iron oxide nanoparticles (MNPs) in two different ways: the direct treatment results in anchoring via catechol groups, where…

1978

Synthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N-[4-(N-methyl-2,4-diamino-6-pteridinylmethylamino)benzoyl] glutamic acid (1a), a widely used antitumor agent, are described. Derivatives of poly(L-lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3–15 mole-%) of substituted repeating units were prepared by polymer-analogous amidation and transesterification of the dimethyl ester of 1a and with N-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate as coupling reagent. By nucleophilic addition reactions of the pteridinyl amino groups under mild conditions, 1a was bound without cross…

1981

In order to investigate the influences of different end-groups on oligomer miscibility with other substances, oligo(propylene glycol)s bearing OH groups (OPG-OH) studied in the previous paper2, were acetylated at both ends (OPG-AC). The limits of miscibility of OPG-AC with oligo(dimethylsiloxane) (ODMS) were measured turbidimetrically. A simple and reliable method for the determination of the critical points from turbidity data is presented. The observed upper critical temperatures (Tc) increase with degree of oligomerization of ODMS (ranging from 1 to 5), whereas Tc shows a minimum when the degree of oligomerization of the OPG-AC is raised (from 1 to 57,5). For lower mol. wt. oligoglycols,…

Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde

2017

This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear…

Effect of propylene glycol on pre- and post-partum performance by dairy ewes

2005

This study was carried out in order to determine the effects, after feeding propylene glycol to Valle del Belice ewes 30 days prepartum and 30 days postpartum, on metabolic profiles, body-condition score, milk yield, milk composition, milk clotting ability and the performance of suckling lambs. Ewes were blocked by parity, body-condition score and previous milk production, and assigned randomly to either a control diet or a diet containing propylene glycol fed at the rate of 80 g/ewe/day (low PG) or 160 g/ewe/day (high PG). Feeding propylene glycol prepartum decreased the concentration of BHBA and NEFA and increased the concentration of glucose in the ewes’ plasma. Milk yield from ewes fed …

Ethylene-vinyl alcohol copolymer (Onyx®) transarterial embolization for post-traumatic high-flow priapism

2016

International audience; We report a case of high-flow priapism treated successfully with superselective embolization of the cavernous artery. A 16-year-old male developed post-traumatic priapism subsequent to a fall causing blunt perineal trauma. He presented to our hospital four days after trauma. Immediately after the injury, he suffered painless sustained incomplete erection. High-flow priapism was diagnosed on the basis of color doppler ultrasonography findings. Computed tomography scan showed a high-flow arterio-venous fistula with feeders from branches of the right internal iliac artery. Selective arteriography of the right internal pudendal artery demonstrated an arterio-cavernous fi…

Embolization with ethylene vinyl alcohol copolymer (Onyx®) for peripheral hemostatic and non-hemostatic applications: a feasibility and safety study

2018

International audience; Background: Onyx® is a liquid embolic agent, which is approved for the treatment of cerebral vascular lesions but still rarely used in peripheral interventional radiology. The goal of this study is to report the feasibility and safety of embolization with Onyx® for peripheral hemostatic and non-hemostatic endovascular procedures.Methods: Retrospective study of all consecutive patients who underwent visceral or peripheral embolization with Onyx® for hemostatic or non-hemostatic purpose in our department between May 2014 and November 2016. Demographic data, clinical presentation, underlying etiology, culprit vessel, endovascular procedure, pain during embolization, out…

Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry

2021

Radiation-sensitive gels are among the most recent and promising developments for radiation therapy (RT) dosimetry. RT dosimetry has the twofold goal of ensuring the quality of the treatment and the radiation protection of the patient. Benchmark dosimetry for acceptance testing and commissioning of RT systems is still based on ionization chambers. However, even the smallest chambers cannot resolve the steep dose gradients of up to 30–50% per mm generated with the most advanced techniques. While a multitude of systems based, e.g., on luminescence, silicon diodes and radiochromic materials have been developed, they do not allow the truly continuous 3D dose measurements offered by radiation-se…